The present invention relates to an image forming apparatus such as a copying machine, a printer and a facsimile machine using an electrophotographic technology, particularly to an image forming apparatus characterized by improved means for sucking toner scattering from a developing device.
The image forming apparatus for forming an image based on the electrophotographic technology generally utilizes powder-like toner for development and image formation.
In many cases, some measures must be taken to prevent toner from scattering in the process of development using powder-like toner. The electrophotographic image forming apparatus is mostly provided with a sealing means for sealing the position where toner is more likely to scatter, or sucking means for sucking toner scattering from the developing device.
The prior art having been disclosed so far includes the art of sealing both ends of a development area using a sealing means (Patent Document 1); the art of discharging a sucked toner in an axial direction, downstream from an opening of a development roller as a developer carrier, using a sucking means (Patent Document 2); and the art for sucking toner coming between magnetic brushes and removing it by a development housing designed in a double structure and a portion corresponding to the magnetic brush provided with a wall to perform rubbing (Patent Document 3). However, the art disclosed in Patent Document 1 has a problem with the degree of sealing of the sealing means rubbed against a development roller. The art described in Patent Documents 2 and 3 have a problem of a carrier, together with toner, being sucked. Patent Documents 2 and 3 have a further problem of how to increase a sucking apparatus and power since the opening for sucking is long in the axial direction. As a result, the installation space, power consumption and noise must be increased. In particular, a non-magnetized area in the vicinity of both ends of the development roller is found in the opening for suction provided close to the development roller, and therefore, toner tends to scatter. Further, air flow caused by rotation of the development roller flows through the development housing, and toner tends to be emitted outside the development housing from the position close to both ends of the development roller. Thus, toner tends to be scattered in the portion close to both ends of the development roller. Patent Documents 2 and 3 do not provide a solution for this problem.
[Patent Document 1] Official Gazette of Japanese non-examined Patent Publication No. 10-48949
[Patent Document 2] Official Gazette of Japanese non-examined Patent Publication No. 2001-117363
[Patent Document 3] Official Gazette of Japanese non-examined Patent Publication No. 4-355481